Cache Read Context Switching in Memory Sub-Systems
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Solution Overview
Problem
Current memory sub-systems face increased latency and complexity due to cache read commands, particularly when snap read commands are received during long sequential read flows, leading to delayed processing and higher priority commands being blocked unless a terminate cache command is issued, which complicates firmware design and increases latency.
Innovation Solution
Implementing a cache read context switch command that allows suspension of pending cache read commands, enabling higher priority snap read commands to be processed without overwriting cache read data, and restoring the cache read context upon completion, thereby reducing latency and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a terminate cache command is issued to process high-priority snap read commands, then the snap read commands can be processed, but firmware complexity increases and latency increases
Solution Approach 1:
The memory device autonomously manages cache read context switching through dedicated hardware circuits (context switch control circuit, cache read control circuit) that automatically suspend, switch, and restore cache contexts without requiring complex firmware intervention. The hardware self-manages the suspension of pending cache read commands, processing of snap read commands, and restoration of cache contexts, eliminating the need for terminate cache commands and reducing firmware complexity.
Solution Approach 2:
A dedicated context switch control circuit acts as an intermediary between the command interface and cache read control circuits. This intermediary hardware component receives context switch commands, coordinates the suspension of pending cache read commands, manages the switching to snap read command processing, and handles the restoration of cache contexts, thereby simplifying the overall control logic and reducing firmware involvement.
2Speed
If a terminate cache command is issued to process high-priority snap read commands, then the snap read commands can be processed, but latency increases
Solution Approach 1:
The system performs preliminary actions by maintaining pending cache read commands in a suspended state rather than completing or aborting them. When a snap read command arrives, the cache read context is already prepared for switching, and the pending commands are held in a ready-to-resume state. This preliminary suspension mechanism eliminates the need for terminate cache commands and reduces the time required to switch between command types.
Solution Approach 2:
The cache read control circuits are designed to dynamically switch between processing pending cache read commands and processing snap read commands based on incoming command priorities. The context switch control circuit enables real-time dynamic reconfiguration of the cache processing pipeline, allowing the system to adapt to changing workload requirements without fixed processing sequences or terminate commands.
3Reliability
If cache read commands are processed sequentially, then data integrity is maintained, but read throughput decreases
Solution Approach 1:
The cache read processing system is segmented into multiple independent cache read control circuits that can operate in parallel. Each control circuit manages its own cache context and can process commands independently. This segmentation allows the system to maintain data integrity within each context while enabling parallel processing of multiple cache read commands, thereby increasing overall read throughput without compromising reliability.
Solution Approach 2:
The system maintains continuity of useful action by keeping pending cache read commands in a suspended而非aborted state. When snap read commands are processed, the cache context is temporarily switched but the pending commands remain intact and can be resumed immediately afterward. This continuous action mechanism ensures that cache read operations maintain data integrity while minimizing idle time and maximizing throughput through seamless context restoration.
Data Source
AI summary
A memory device includes a memory array configured with a plurality of memory planes, and control logic, operatively coupled with the memory array. The control logic receives, from a requestor, a plurality of cache read commands requesting first data from the memory array spread across the plurality of memory planes and receives, from the requestor, a cache read context switch command and a snap read command requesting second data from one of the plurality of memory planes of the memory array. Responsive to receiving the cache read context switch command, the control logic suspends processing of the plurality of cache read commands and processes the snap read command to read the second data from the memory array and return the second data to the requestor.